But, its being lost is a big gain for local birders. Armed with binoculars, scopes and cameras, they are flocking to the shoreline of the Niagara River and climbing the observation tower at Erie Basin Marina for a glimpse or, better yet, a flyby from the rare, gull-like tropical diving bird.

She – it’s a female – is a first for Buffalo and Ontario and for most of the local birders. The Brown Booby normally is found along the coasts of Central America, and it is unusual to spot one anywhere in the United States, except in Florida and Southern California.

“Its appearance here, well, there’s no explanation. The probability of one here is in the millions,” said Dominic Sherony, of Fairport, who was at the marina Wednesday with a telephoto setup.

The bird was first reported Monday and was seen again Tuesday and Wednesday afternoon, so a pattern may be developing.

Sherony and other seasoned birders discounted the possibility that the booby is a “plastic,” the term for rare birds that have escaped from captivity into a foreign environment.

“It’s not a bird kept in zoos or aviaries,” Sherony said. “This is really mysterious.”

At the same time, the booby’s sighting earlier this week was fortuitous. Amateur birder Sue Barth had been hoping to add another bird, a jaeger, to her “life list,” the record kept of all birds spotted and/or heard, when she and fellow bird-watcher Jim Pawlicki headed out into some nasty weather Monday morning.

“I’ve been on a mission to find a jaeger, and they only come out when the weather is really horrible,” Barth explained.

“Then Jim saw this bird. Just being there was a stroke of luck. The conditions were so horrible, I don’t know how he even spotted it.”

The Brown Booby was hanging around on Donnelly’s Pier, where the lake flows into the Niagara River. It was with a group of double-crested cormorants, a common local waterbird similar in size and coloring to the booby.

“He was superexcited. As first he thought his eyes were deceiving him, but they weren’t,” Barth said.

Bird-watchers label this kind of find a “mega,” a bird that you never, ever expect to see in the place where you are seeing it.

When news of the sighting hit birding’s social media, dozens of people from Ontario and Western New York headed out to try to add the brown-and-white oddity to their lists.

David M. Mark, a professor of geography at the University at Buffalo, has seen the Brown Booby before in Florida, and was watching it Wednesday afternoon.

“When it turns to preen its back feathers, you see its yellow beak,” Mark said, explaining how they could identify it.

Laurie Dann, of Buffalo, said this was her second Brown Booby this year. The first was at Bodega Bay in California.

“It’s totally illogical to find one here,” she said. “It’s like a scavenger hunt to find one of these birds.”

The search is made easier, thanks to texting and message boards, which have been burning up on both sides of the border. After being spotted for several days, things may get even busier.

“It’s hard to know if it will stay around here, but with the weather pattern we’re having, it could be a while longer,” Chris Hollister, of Buffalo, said while he was patiently watching the water. “And it could have been here for weeks before Jim spotted it.”

No one could come up with any good reason why a coastal bird from the tropics would appear in Buffalo in October, even in an autumn as unseasonably warm as this.

“There’s a tropical storm in the Gulf of Mexico,” Sherony said, “and that might have something to do with it. But this bird is an adult – which is really rare.”

Vicki Kadow, who came from Amherst with Roger Johnson to see if they could spot the bird Wednesday morning, was concerned about how the booby’s adventure might turn out.

“What’s likely to happen to a solitary bird here, so far from its habitat?” she asked.

Sherony and Hollister weren’t encouraging. The booby dines mostly on squid and ocean fish, and may have trouble finding enough to eat in the lake and river.

“Cormorants don’t stay here, either,” he said. “They winter on the coast. If [the booby] finds enough to eat, it could go with them.”

Otherwise, the bird’s fate may live up to its name. Bird-identification websites say it was first called a “booby” because it was not very intelligent and was unafraid of people, who found the animals very easy to catch.

Also, when found in large groups, they are referred to as a “congress.”